For any proposed development in the County a detailed floodplain study must be performed for all drainage areas greater than 100 acres that do not currently have detailed FEMA Flood Insurance Study flood profiles or elevations. The purpose of a detailed floodplain study is to determine the extent to which flooding would occur during the 100-year storm, and to map the 100-year floodplain boundaries, also known as the 100-year flood inundation zone. Drainage easements must be designated on site to preserve the inundation zone. Calculations for floodplain studies should be based on land use as outlined in the Comprehensive Plan.
All Floodplain Studies should be prepared utilizing NRCS and USACE Hydrologic methods unless otherwise approved by the Virginia Stormwater Management Program Administrator. NRCS Hydrology consists of Technical Release Number 20 (TR-20) and Technical Release Number 55 (TR-55) and other NRCS applications. USACE hydrology consists of the HEC-1 and HEC-HMS computer models,
Construction of drainage improvements, stormwater management facilities, and/or modifications within a FEMA designated 100-year floodplain should be avoided to the maximum extent practicable. When this is unavoidable, all improvements or modifications shall be in compliance with all applicable regulations under the National Flood Insurance Program, 44 CFR Part 59 and shall be engineered for structural integrity during the 100-year storm event by the primary flooding source or secondary source, whichever yields the most conservative design. Most construction activity proposed in the 100-year floodplain must be approved by the Board of Supervisors through the Special Exception process. It also triggers the requirement for the submission of a detailed Floodplain Study, including all the supporting documentation of the effective (if applicable), and the pre- and post-development conditions, for review by the County. Calculations for the pre-development condition shall be based on what exists just prior to development and not ultimate conditions based as outlined in the Comprehensive Plan. Modifications to the effective regulatory floodplain will require final FEMA determination at the owner’s expense.
Any floodplain study performed for the purpose of revising the FEMA-designated 100-year floodplain on FEMA’s Flood Insurance Rate Map (FIRM) for Fauquier County must be reviewed and approved by the County prior to submission to FEMA. The County requirements for floodplain studies can be found in the Design Standards Manual and the Floodplain Study Checklist. FEMA floodplain study submission requirements can be found on the National Flood Insurance Program (NFIP) website.
Submission Requirements for Floodplain Study Application to County
- Land Development Application with original signatures
- $500 Fee
- Floodplain Study Checklist signed by surveyor or engineer
- 4 copies of floodplain study plan
- 4 copies of full report
- FEMA MT-2 Application form
- Flash Drive with digital copies of the hydrologic and hydraulic models as well as individual PDFs of all submission materials - do not include any financial information (i.e. copy of checks or the fee calculation sheet)
The County will review the Floodplain study for conformance with all requirements. Once the study is approved by the County, the Floodplain Administrator will sign the MT-2 Form 1, known as the Overview & Concurrence form, and the applicant may proceed to submit the application to FEMA for final approval.